Tuesday, March 29, 2016

I found a few of these tiny, elongated brachiopods while searching the Bois d'Arc formation. I believe it is called Camarotoechia haraganensis. It's a small shell that is longer than it is wide. Both valves are equally convex with strong costellae (or ribs as I sometimes call them). The sides of each valve are fairly flat and nearly at a right angle to the rest of the valve. On the pedicle valve, the beak extends well past the brachial valve with little to no curving with the umbo at the very tip, perpendicular to the rest of the beak.

Pedicle valve

Anterior

Brachial Valve

Posterior

Profile

These are much larger specimens that those that I have from the Haragan formation and could represent a different species. The only other similar species, that I can find reference too, is Rhynchospirina maxwelli but that shell is wider and has finer costellae.

Monday, March 28, 2016

This highly decorated shell has a very long name: Kozlowskiellina (Megakozlowskiella) velata. It is related to Kozlowskiellina perlamellosa which is found in the Helderberg fauna of New York. The shell is triangular to half moon shaped with each convex valve featuring coarse plications (generally three on each side of the fold and four on each side of the sulcus). The shell is further decorated with strong concentric growth lamellae. The pedicle valve recurves, extends past the brachial valve and has a wide, triangular interarea and narrow triangular dethyrium.

Brachial valve

Anterior

Pedicle valve

Posterior

Profile

Compare this specimen to one from the Haragan formation which underlies the Bois d'Arc formation.

I found the specimen shown on this page in the Bois d'Arc formation (Cravatt member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc and Haragan formations interfinger with each other and are roughly the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

Friday, March 25, 2016

As I mentioned in the previous post, I found a few specimens of pelecypod in the Bois d'Arc formation that are just casts or molds that I can't really ID.

This specimen looks like it may belong to the genus Nucula or Grammysia.

This next specimen looks similar to a Modiomorpha sp.

This last specimen is a real mystery to me. There is no surface ornamentation preserved but both valves are present. It has very convex valves with what appears to be a flat hinge line.

I found the specimens shown on this page in the Bois d'Arc formation (Cravatt Member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc overlies the Haragan formation but both are the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

Tuesday, March 22, 2016

I found a few pelecypod mold and casts during my hunt among the rocks of the Bois d'Arc formation in Oklahoma. All are without shell material and some have little detail with which to help identify them. One group of specimens does have some detail and appears to belong to the genus Actinopteria and may be A. textilis. The fossils I found are all of single valves but show impressions of the interior or exterior of the left or right valves. The shells have an overall rectangular outline with a central lobe that starts in one corner and widens as it extends diagonally to another corner.There is a small, short ear that extends along the hinge line and connects to the body of the shell for a short distance. Preserved impressions of the shell surface decoration shown radiating ribs that are crossed with concentric growth lines. Both features have some relief to them to that the shell surface looked a little like a checker board.

Specimen 1 - External mold

Specimen 2 - Internal cast

This may be a different species from the two specimens shown above. The ear is much longer and connects with the body of the shell for a greater distance as well. It could be an Actinopteria communis as that has features that appear to fit this fossil. I made this ID after viewing plate 76, fig. 2-4 in "Devonian Plates". Maryland Geological Survey. Johns Hopkins Press, 1913

I found the specimens shown on this page in the Bois d'Arc formation (Cravatt Member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc overlies the Haragan formation but both are the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

I used the book "Palaeontology of New York". Hall, James, George Bancroft Simpson, and John Mason Clarke. Vol. 3. C. van Benthuysen, 1859. Part 2, pl. 53. to help ID the first two specimens as I can't locate any references for pelecypods from the lower Devonian of Oklahoma.

Saturday, March 19, 2016

When I'm out collecting I often pick up anything that looks like it might be a fossil and sometimes I know what it is while other times it just looks similar to another shell. Such is the case with Coelospira virginia. This is a very small shell that I probably thought was an Atrypina sp. when I tossed it into my collecting bag. It wasn't until I got home and really looked closely at it that I saw there was a difference. White it does have the same rounded shape as Atrypina sp. with a wide fold and sulcus, the radial ribs are narrower and the margin is flat rather than following the curve of the rib. This was the key feature that inspired me to look for another match. I found a good match while going through "Stratigraphy and Paleontology of the Hunton Group in the Arbuckle Mountain Region, Part V - Bois d'Arc Articulate Brachiopods " Amsden, 1958, Oklahoma Geological Survey Bulletin 82 on plate V, fig. 39.40.

Brachial valve

Anterior

Pedicle valve

Posterior

Profile

I found two specimens of Coelospira virginia (one of which is shown on this page) in the Bois d'Arc formation (Cravatt Member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc overlies the Haragan formation but both are the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

Wednesday, March 16, 2016

Atrypina hami is an easy brachiopod to ID due to the wavy nature of the shell. It has a generally rounded appearance with flat to slightly concave brachial valve and a convex pedicle valve. The pedicle valve extends beyond the pedicle valve and curves just slightly at the umbo. both valves have widely spaced, concentric growth lines and a handful of very wide ribs that affect the margin of the shell. It's this wavy appearance and the obvious growth lines that make this brachiopod unique.

I found the specimen shown on this page in the Bois d'Arc formation (Cravatt Member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc overlies the Haragan formation but both are the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

Sunday, March 13, 2016

A highlight of my collecting trip to the Bois d'Arc formation was finding the tiny brachiopod Dicoelosia varica. It is somewhat common in certain horizons of the formation and I probably picked up a dozen or more specimens loose plus a number of specimens on matrix. such as the one below with three specimens.

Dicoelosia varica is a member of Order Orthida and is very easy to identify. It is a small shell shaped like the letter "V" with two distinct. rounded lobes. Between the two lobes the shell pinches down and the margin retreats towards the umbo. There are very few brachiopods that have this kind of shell structure with Pygites sp. being the only other similar looking species I can think of. Both valves of the shell have thin radial striae and thin concentric growth lines. The pedicle and brachial valves both extend past the margin at the posterior and then double back at an angle to meet at the hinge line. The pedicle valve has a triangular shaped delthyrium through which the pedicle muscle once extended.

Brachial valve

Anterior

Pedicle valve

Posterior (pedicle valve on top)

Posterior (pedicle valve on bottom)

Profile

Compare these specimens with the smaller sized specimens I have from the Haragan formation.

I found the specimen shown on this page in the Bois d'Arc formation (Cravatt Member)
near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois
d'Arc overlies the Haragan formation but both are
the same age (Devonian, Lockhovian stage). They are both
roughly correlative to the Helderberg fauna of New York and thus are
contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

Thursday, March 10, 2016

I found a number of these round, nut like brachiopods while searching the Bois d'Arc formation in Oklahoma. They are called Sphaerirhynchia lindenensis and seem to have a bit of variability in their features. Overall the shells are rounded to subpentagonal in outline and rectangular to square in cross section. Both valves are convex and have strong, rounded ribs decorating the surface. The margins of both valves are flat except along the anterior margin where the shell develops "teeth" that correspond to the raised ribs on each valve. These "teeth" alternate with the valve below and interlock when closed. This same pattern is present on the fold and sulcus which is entirely expressed in the anterior margin. The pedicle valve has an umbo that extends past the brachial valve and masks the interarea.

I mentioned before that Sphaerirhynchia lindenensis is variable in appearance. This is expressed in the degree of convexity of the valves and width of the ribs. These variations could represent different species but as yet I have not found any literature that describes the fauna of the Bois d'Arc other than Amsden's original paper.

Specimen #1 - Brachial valve

Anterior

Pedicle valve

Posterior

Profile

Specimen #2 - Pedicle valve

Anterior

Brachial valve

Posterior

Profile

Specimen #3 - Brachial valve

Anterior

Pedicle valve

Posterior

Profile

I found the specimen shown on this page in the Bois d'Arc formation (Cravatt Member)
near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois
d'Arc overlies the Haragan formation but both are
the same age (Devonian, Lockhovian stage). They are both
roughly correlative to the Helderberg fauna of New York and thus are
contemporaneous with the Coyemans, Kalkberg and New Scotland formations.

About Me

I'm a 40-something, life long student of Geology living in Philadelphia. My interests include Photography, Architecture and History among other things. When not cleaning my recent finds you'll find me in my backyard Hybridizing Daylilies or working in my garden. This Blog is an outlet for me to express my interest in fossils, catalog my collection and coalesce my thoughts and research into a useful medium.